Major league teams are adopting new technology allowing fans who have already bought tickets to upgrade their seats.

Several tech vendors are marketing mobile Web platforms through which fans can use their smartphones to move to better locations in the stadium at reduced prices. The technology helps teams move unsold inventory, resell seats left empty by no-shows and capture data on ticket buyers and their seating preferences, according to clubs using the systems.

The Los Angeles Galaxy, an early adopter, has generated revenue of $750 to $1,200 a game this season by selling seat upgrades through Experience, an Atlanta-based company, said Kelly Cheeseman, AEG Sports’ senior vice president of ticket sales and service.

In addition, Experience has deals with the San Jose Earthquakes and Chicago Fire from MLS; Los Angeles Clippers, Atlanta Hawks and Boston Celtics of the NBA; MLB’s Atlanta Braves; and the University of Tennessee. Company investors include Pat Battle, formerly with IMG and the Collegiate Licensing Co., and Billy Payne, chairman of Augusta National Golf Club.

The Galaxy consistently sells the 75 to 100 tickets it reserves for seat upgrades at Home Depot Center after testing the program in 2011, Cheeseman said.

Most upgrades are tied to club seats and field-side seats regularly priced at $125 and $200 a game, he said. The discounts agreed to by the Galaxy and Experience, depending on the game and tickets already sold, typically run from $5 to $50 in additional costs for the ticket buyer.

Pogoseat is testing its service at Stanford.

To make those upgrades available, the Galaxy removes inventory not projected to sell from Axs, its ticketing system, and transfers it to Experience’s system. The day before a game, Experience sends emails to all fans that have already bought tickets, alerting them to the availability of seat upgrades. Those interested register online and complete a short survey on their seating preferences before being placed in a virtual queue tied to their choices. The Galaxy has averaged 300 requests a game for seat upgrades, Cheeseman said.

Those fans receive an email with a link to the upgrade. Fans choosing to upgrade pay by credit card on their smartphone and receive a message allowing them to validate the purchase, said Experience President Ben Ackerman. The mobile screen serves as their new ticket.

In San Jose, the Earthquakes use Experience to resell the seats of no-shows as well as to move unsold inventory on game days at Buck Shaw Stadium, said team President Dave Kaval. In general, 10 to 50 seats are sold as upgrades, Kaval said.

Elsewhere, Pogoseat, a newer startup, is testing a similar service at Stanford University football games this fall with an eye toward using it to resell seats for men’s basketball games at Maples Pavilion. The Pac-12 school has no-show issues with donor seats going unoccupied for lesser opponents and wants to fill those locations, said Dave Sertich, a business strategy analyst with Stanford athletics. To date, no deal has been signed, Sertich said. The tests are being done with a Web-based platform as Pogoseat develops a mobile application for future use, said Evan Owens, Pogoseat’s co-founder and CEO.